This study addresses several questions:1)what will be the maximal tolerated dose of AAV-CFTR in the lungs of pts., with mild lung disease2)will AAV-CFTR vector expression be detectable in the lungs of CF pts. after receiving a dose that results in no toxic effects3)what will be the efficiency & duration of expression of AAV-CFTR after administratin to the respiratory epithelium in the nose. The answers to these questions will provide vital information relevant to any future AAV-based gene therapy.